1. Field of the Invention
The present invention is directed to an introducer sheath having a hemostatic valve that can maintain hemostasis around surgical implements and medical devices having a wide variety of cross-sectional diameters during surgical procedures.
2. Background of the Invention
Introducer sheaths are used to assist in the introduction of guide wires, surgical implements, and medical devices into a patient's vascular system (typically an artery) for many different types of intravascular procedures. The introducer sheath and its associated dilator are designed to penetrate the skin and wall of the blood vessel and be positioned within the blood vessel so that surgical implements and medical devices may be advanced and withdrawn through the introducer sheath. In this way, even when multiple surgical implements and/or medical devices are used in a single procedure, there is a single placement of the introducer sheath through the skin and vessel wall.
Introducer sheaths typically include valves that generally fall into two basic categories: passive and active. A passive valve generally relies on the deformation of a resilient sealing body by the implement or medical device inserted through the valve to form the desired fluid tight seal. An active valve includes a mechanism that moves a sealing body into contact with the traversing implement or medical device.
A wide variety of passive and active valve structures for introducer sheaths have been proposed. While these structures have met with varying degrees of success and acceptance, they generally have suffered from a common disadvantage: sealing bodies (whether passive or active) that provide an effective hemostatic seal with a guide wire and with a wide range of cross-sectional diameters of surgical implements and medical devices. Passive valve structures tend to impose substantial frictional forces on at least some sizes of traversing implements, e.g., the larger sizes, thereby making is difficult for the user to insert and withdraw such implements into and out of the introducer sheath.
Despite the wide variety of introducer sheaths that have been proposed, the use of simple fixed o-rings or grommets for the valve remains common. While these simple sealing devices accommodate only a very narrow range of surgical implement diameters, the seals provided within that range tend to impose frictional forces that are low. In many cases, hemostasis cannot be achieved due to inadequate sealing, and many introducer sheaths leak when only a guide wire is placed in the introducer sheath.
Endovascular surgical procedures, such as the endovascular placement of vascular stents, grafts, stent-grafts, and other endoluminal prostheses for the treatment of abdominal aortic aneurysms and other vascular diseases, have been developed that place even more stringent demands on the introducer sheath. Such endovascular prosthetic placement procedures generally involve the use of relatively large prosthetic deployment catheters, typically having a French gauge in the range from about 11 Fr to about 26 Fr.